Electrical resistor and the like



Dec. 11, 1956 J. J. CERNY ELECTRICAL RESISTOR AND THE LIKE Filed Sept. 8, 1954 7 him l/Vl/E/VTOR JOSEPH J GER/V) ar jw Unite States Patent ELECTRICAL RESISTOR AND THE LIKE Joseph J. (Ierny, Chicago, Ill.

Application September 8, 1954, Serial No. 454,744

7 Claims. (Cl. 201-62) This invention relates to resistors and the like, and more particularly it relates to resistors and the like having variable resistance. Specifically this invention relates to improvements in adjustable terminal components used in combination with resistors and the like of variable resistance.

conventionally, resistors of the type with which the instant disclosure is concerned comprise a core about which resistance wire is Wound. A pair of fixed bands having outwardly extending terminals are secured at the ends of the resistance wire and about said core. A refractory material envelops said resistance wire and portions of the bands. The refractory envelope has provided therein an opening or window through which a portion of the wound resistance wire is exposed. An adjustable terminal component customarily comprising a band which is adjustably secured about the refractory coating carries a contact element which engages the exposed resistance wire at selected positions.

In conventional devices of the class described the adjustable terminal components do not completely provide for protection of the exposed resistance wire from damage during adjustment. Also, frequently it is difficult to adjust the terminal components when the resistors are hot. Additionally, it is often diflicult to properly center the contact elements of conventional devices in selected positions.

It is an object of this invention to provide a device of the type described in which there is provided means to cause the contact element to spring away from the exposed resistance wire when the terminal component is loosened for adjustment to thereby preclude damage of the exposed resistance wire.

It is further an object of this invention to provide a terminal component which is simply and easily adjustable and which experiences a minimum resistance from the resistor against longitudinal movement.

It is a yet further object of this invention to provide a terminal component in combination with a resistor of the type described which can be adjusted simply and speedily in selected positions, even though the resistor is hot.

Still further, it is an object of this invention to provide a resistor of the variable resistor type in which the proper alignment of the contact element and the exposed resistance wire is achieved easily by providing manually grippable means aligned in predetermined relationship with the contact element.

Other and further objects of this invention will become apparent from the following description and appended claims, reference being had to the accompanying drawings and numerals of reference thereon.

On the drawings:

Fig. 1 is a side elevation of one embodiment of the instant invention, parts of the refractory coating being broken away for the purpose of illustration.

Fig. 2 is a section view taken substantially on the line 2-2 of Fig. 1 and looking in the direction of the arrows.

Fig. 3 is a section view taken substantially on the line 3--3 of Fig. 1 and looking in the direction of the arrows.

Fig. 4 is a sectional view similar to Fig. 3, showing the terminal component loosened so that the contact element is disengaged from the resistance wire.

Fig. 5 is a view taken substantially on the line 55 of Fig. 3 and looking in the direction of the arrows.

Fig. 6 is a view taken substantially on the line 66 of Fig. 5 and looking in the direction of the arrows.

Referring now more particularly to the drawings, a resistor or resistance element, generally designated by the numeral 10, comprises a preferably hollow tube or core of porcelain or other refractory material. In the embodiment illustrated in Fig. 1, the encircling portion of a conductive band 12 of copper or other suitable material is secured about the core 11 at one end thereof. The encircling portion of a second conductive band 13, similar to the first identified conductive band 12, is secured about the core 11 adjacent the opposite end thereof. Respective bands 12 and 13 are fastened in position by means of fasteners 14 and 15, such as rivets, or the like.

A resistance wire 16 is wound about the core 11 between said bands; and the opposite end portions 17 thereof are secured to respective bands 12 and 13 by soldering or equivalent means. (One of such securances is illustrated in Fig. 1 and the other in Fig. 2.)

The metal bands 12 and 13 are provided with apertured, outwardly extending terminal elements 18 and 19, each of which is illustrated as being integral with respective bands 12 and 13. A lead wire generally represented by the numeral 20 is shown connected to terminal element 18, in Fig. 1.

An envelope or coat 21 of insulating material such as vitreous enamel is applied on and about the core 11, the encircling portions of bands 12 and 13 and portions of the resistance wire 16; and said envelope 21 has provided therein an elongated axial extending slot or window 22 through which another portion of the wound resistance wire 16 is exposed.

An adjustable terminal component or contacting device generally designated by the numeral 23, is mounted about the resistor 10 and is adapted to be adjusted longitudinally and secured in adjusted positions in electrical contact with the exposed portion of the resistance wire 16.

The terminal component 23 comprises an encircling conductive band portion 24, secured about the resistor 10 by means of a fastener 25, such as a rivet or the like, as illustrated in Figs. 5 and 6. An apertured terminal end 26 extends outwardly from the band portion 24. A lead wire generally designated by the numeral 27 is shown connected to the terminal end 26.

The encircling band portion 24 has a struck-out or outwardly offset section or spring 28. It is preferred that said struck-out portion 23 be normally curved or arched, but it may be of any other suitable geometric configuration, such as angular. If said section 28 is curved, the normal radius of curvature is preferably, although not necessarily, smaller than the normal radius of curvature of the encircling band portion 24. The struck-out or offset portion or spring 23 carries, substantially at the center thereof, a metal or conductive contact element or button 29 which is adapted to selectively engage portions of the wire 16 exposed through the window or slot 22.

The inner end of a stem 30 is secured by a means such as riveting or the like, to the encircling portion 24 at a position which is preferably substantially diametrically opposite from the contact element 29. Stem 30 carries, preferably in axial alignment therewith, an outwardly extending screw 31. A spacer or bridge 32 comprising a pair of legs or spacing elements 33, 33, the inner ends of which are curved to the contour of the envelope 21 and the outer ends of which are connected by 3 an apertured transverse or bridging element 34, is mounted about the screw 31 as illustrated in Figs. 3, 4, and 5. A manually operable nut 35 is threaded on the outer end of screw 31 and the inner end thereof bears against the transverse or bridging element 34 of the spacer 32.

Therefore, as the nut 35 is gripped and tightened (rotated clockwise with respect to Fig. 6), the encircling portion 24 is drawn to the position of Fig. 3, the contact element 29 engaging a portion of the wire 16 exposed through window or slot 22. As the nut 35 is loosened (rotated counter-clockwise with respect to Fig. 6), the screw 31 moves inwardly toward the core and the band portion 24 tends to assume its normal configuration. Simultaneously, the struck-out or outwardly offset portion 23 carrying the contact button 29 has the tension thereon released and it too tends to assume its normal configuration. If the struck-out or offset portion 28 is curved so that the normal radius of curvature thereof is less than the radius of curvature of the remainder of encircling portion 24, the tendency of the struck-out or outwardly ofiTset portion 28 to spring away or outwardly from the resistor 10, causing the contact element to spring away from the exposed portion of the resistance wire 16 is augmented. It is then possible to make longitudinal adjustment of the adjustable terminal component 23 without damaging the wire merely by gripping the nut 35 to cause engagement of the inner ends of the spacing elements 33, 33 with the ceramic coat 21 and sliding the contact device longitudinally to the desired position. Because the contact element lies substantially on the same diameter as the axis of the stem 30 and screw 31, the contact element may be quickly and easily secured against wire 16 in selected positions. This feature of rapid and easy adjustability confers greater significance to the instant invention when it is considered that numerous adjustments of the adjustable terminal component or contacting device 23 are required at times when the resistor is hot.

Inasmuch as many changes can be made in the foregoing construction, and inasmuch as many variations therein could be proposed without departing from the spirit and scope of this invention, it is intended that all matter contained herein shall be considered as illustrative only and not in a limiting sense.

I claim:

1. An electrical resistor and the like having an insulating coat having an opening through which a portion of the resistance wire of said resistor is exposed, terminal means including a selectively movable encircling element about said resistor, portions of said encircling element being under different degrees of force when said terminal means is in contacting position; a contact element on one portion of said encircling element; a stem-1ike element extending outwardly from said encircling element, and being secured thereto at its inner end; an aperturecl spacer element, the stem-like element extending through said spacer element and grippable means mounted on said stem-like element whereby the tension applied to said encircling element may be varied.

2. in a resistor and the like including at least one fixed terminal the combination of a core, resistance Wire about said core and a movable terminal component selectively engageable with said wire, with a manually operable means including a pin and a spacer, said pin adjustably extending through said spacer, said spacer straddling an encircling portion of said terminal component whereby drawing of said pin outwardly causes engagement of said terminal component With the resistance wire.

3. A resistor and the like having an adjustable terminal component substantially as recited in claim 2 and further characterized by the fact that said terminal component comprises a pair of curved springs sections having difierent normal radii of curvature; contact element carried on the section having the smaller radius of curvature and being in substantial diametric alignment with said pin.

4. As a subcombination in a resistor and the like having variable resistance, a longitudinally adjustable terminal component encircling the resistor; a contact element carried on the encircling portion of the terminal component; a threaded pin secured to the encircling portion of said terminal component, the longitudinal axis of said pinbeing disposed in substantial diametric alignment with said contact element; a nut on said pin, and a spacer between the nut and the resistor whereby upon tightening of said not said pin is drawn through said spacer.

5. An adjustable terminal component for resistors and the like having portions of the resistance Wire exposed and comprising an encircling element comprising a pair of spring sections under different tensions, said spring lying in different planes of curvature; a contact element carried in the outermost of said spring sections, and means for drawing said contact element into engagement with the exposed wire including a spacer straddling the innermost of said spring sections, a pin extending through said spacer whereby the sections can be held under desired tension.

6. A resistor and the like having an adjustable terminal component, substantially as recited in claim 2, and further characterized by the fact that said terminal component comprises a pair of curved spring sections, one thereof normally positioned outwardly from the normal configuration of the other thereof; a contact element carried on the outward section and being in substantial alignment with said pin.

7. As a subcombination in an electrical resistor and the like having variable resistance, a longitudinally adjustable terminal encircling said resistor; a contact carried on the encircling portion of the terminal; spacer means straddling said terminal and adjustable tension applying means having a component extending through said spacer whereby aid terminal is releasably secured in adjusted positions on said resistor.

References (Jilted in the file of this patent UNlTED STATES PATENTS 1,919,061 Hardwick July 18, 1933 FOREIGN PATENTS 550,336 Great Britain -c Ian. 4, 1943 

